The effects of EGR and blend fuels on particulate emission were studied in CI engine.

EGR ⩽ 20%, gasoline or n-butanol increases total particulate number concentration.

EGR ⩾ 30%, gasoline or n-butanol reduces total particulate number concentration.

As EGR ratio increased, the particulate mass concentrations of four fuels increased.

Gasoline or n-butanol increases the ratio of sub-25 nm particles number concentration.